Printers are peripherals acting as output device widely used for data transfer such as a text or figure from digital files to a physical form like paper. The main types of printers are matrix, thermal, and inkjet, being colored or monochromatic.
However, matrix printers are noisy and inkjet printers do not allow high-speed printing. Thus, the use of thermal printers increased very much over past years, particularly in points of sales, banking terminals, and label printing.
Thermal printers are conventionally composed by a support for printing paper, for instance, from a paper roll, a thermal printing mechanism, and a cutting mechanism, besides cabinet, controlling board, feeding source, and accessories.
Thermal printing mechanisms consist of mechanisms comprising at least one thermal print head and platen roller, which in conjunction heat the desired parts providing darkening of such parts on paper, preferably in thermal paper. Usually, a stepper motor and gears are used to promote the platen roller motion which, then, makes thermal paper to go forward. The thermal printing mechanism can also use a thermal film that, when heated, colors the paper to be printed. Thermal head is a device composed by a matrix of resistances or another element that irradiates heat, in which electrical signals from the controlling board are converted into heat in specific points of the matrix according to what is desired to be printed. Platen roller is pressed on the posterior side of the paper in order to guarantee contact between thermal head and paper, needed for printing.
Cutting mechanisms employed in printers vary from simple small saw, positioned near paper output so that operator cuts paper, to more elaborate cutting mechanisms with automatic activation such as guillotine, circular or helicoidal blades.
Cutting mechanisms like guillotine consist of two relatively flat blades, being one fixed and the other movable. The blades are pressed one against the other by one or more springs, so that by activating the movable bade by a motor and a set of gears the cut is done, such as the sectioning mechanism disclosed on the international application published under no. WO 2005/090027 A1.
Usage of thermal printing mechanisms is convenient due to the quality and speed propitiated. However, conventional mechanisms present difficulties to the operator mainly at the moment of changing the paper roll, because both thermal head and platen roller are fixed to the body that consists of the only chassis in these conventional printers, wherein the operator must manually open the printing mechanism, putting the thermal head away from platen roller, and manually insert paper through printing mechanism and cutting system in a delicate and slow process. In busy establishments, such as big department stores or even fast food chains, these minutes which operator wastes changing the paper roll may represent significant losses of profit by the end of the day. Besides, the waiting time can make clients unsatisfied with the establishment.
In background art there are, thus, several constructive arrangements aiming at making paper change easier and faster. Below, there are some arrangements that propose different dispositions of thermal mechanism and cutting mechanism that have influence on said changing of paper.
For example, patent published under U.S. Pat. No. 6,682,239 B2 discloses a thermal printer unit including a set of thermal head and a platen roller. The Platen roller reception openings disclosed comprise vertical grooves with superior openings, horizontal grooves extending from inferior vertical grooves opposite to thermal head and a projected part above the horizontal fitting towards thermal head. In such openings, platen roller edges are fitted, initially passing through vertical grooves and locating in horizontal grooves, being indirectly pressed by thermal head spring. During printer functioning, the part above horizontal fitting, together with thermal head inclination, provides thermal head positioning in relation to platen roller and printer locking. For printer opening, by means of external force action generated by operator, platen roller edges slide in horizontal and vertical grooves, pushing thermal head and releasing the platen roller passage for printer opening.
Patent published under U.S. Pat. No. 6,758,614 B2 discloses a printing mechanism with platen roller in a chassis provided with a small rotation movement in relation to a second chassis fixed to the covering. Thermal head is disposed on printer body and a lever is disposed on platen roller movable chassis that moves when printer is closed.
Patent published under U.S. Pat. No. 6,118,469 discloses a thermal printer having printer mechanism vertically positioned and, above it, a cutting mechanism with a slight inclination in relation to horizontal direction, wherein thermal head of printing mechanism and movable blade of cutting mechanism are disposed on printer body, and platen roller and fixed blade are positioned on the cover.
Patent application published under number JP 2004-074812 discloses a printer equipped with thermal head of printing mechanism and movable blade of cutting mechanism positioned on printer body, and platen roller and fixed blade are positioned on printer cover by means of a movable chassis pressed by springs. The cutting mechanism is horizontally positioned above the printing mechanism, which is vertically positioned. During opening and closing of printer, the movable chassis of printer cover suffers a small movement for releasing and fitting the mechanisms in the correct position.
Patent application published under number JP 2004-268207 discloses a printer with cutting mechanism like scissors with fixed blade located on body and movable blade located on printer cover. Even if the cutting mechanism stops during cutting movement, printer cover still can be open because the movable blade, that slides on fixed blade during cutting, is located on the cover.
Patent application published under number WO 03/064163 A1 discloses a printer that also tries to solve problem of printer opening, positioning the movable blade on the printer cover and positioning the fixed blade on a second cover disposed on the frontal part of the printer.
Other documents of the background art relate to vertical cutting mechanism such as patent application published under numbers US2005/0162501A1, KR10-2001-0039109 and EP0993955A1.